Because IdHashShardingStrategy fails after 1.7m ID is reached I decided to use my own version of strategy. I set up property common.hibernate.search.blogentry.sharding_strategy = com. ... .IdShardingStrategy and didn't work for me. As I checked problem exist in DirectoryProviderFactory and the way how properties are created ( new Properties( defaultProperties ) ). This constructor and the way how default properties are stored in this Object this both together doesn't work well. Problem exist:

//define sharding strategy
IndexShardingStrategy shardingStrategy;
Properties shardingProperties = new Properties();
for (Map.Entry entry : indexProps[0].entrySet()) {
if ( ( (String) entry.getKey() ).startsWith( SHARDING_STRATEGY ) ) {
shardingProperties.put( entry.getKey(), entry.getValue() );
}
}
String shardingStrategyName = shardingProperties.getProperty( SHARDING_STRATEGY );
if ( shardingStrategyName == null) {
if ( indexProps.length == 1 ) {
shardingStrategy = new NotShardedStrategy();
}
else {
shardingStrategy = new IdHashShardingStrategy();
}
}
else {

in this loop "for (Map.Entry entry : indexProps[0].entrySet()) {" this set is just empty so custom properties for sharding have been ignored.

Workaround:

Instead using new Properties(defaultProps) I'm using method:

private static Properties createProperties(Properties indexSpecificDefaultProps) {
Properties properties = new Properties();
properties.putAll(indexSpecificDefaultProps);
return properties;
}